You know, because this one is so disconnected from the space wars and politics, I think you could probably read it without the rest of the series. The two viewpoint characters are Jole (the surviving dude of the threesome), who's never been a POV before and so would be as new to old fans as to you, and Cordelia (the woman), who has been, but it's been several decades in series-internal-chronology, and so is somewhat new too. There's a certain amount of assumed knowledge of the background worldbuilding (one of the big themes of the series is culture clashes between planets, so there's a lot of 'of course you would say that, you're so Betan' or 'ugh, Barrayans are all the same'), but I think it wouldn't be too hard to pick up from context.